class Solution:
    def merge(self, nums1, m, nums2, n):
        """
        :type nums1: List[int]
        :type m: int
        :type nums2: List[int]
        :type n: int
        :rtype: void Do not return anything, modify nums1 in-place instead.
        """
        pos = m + n - 1
        m -= 1
        n -= 1
        while m >= 0 and n >= 0:
            if nums1[m] > nums2[n]:
                nums1[pos] = nums1[m]
                pos -= 1
                m -= 1
            else:
                nums1[pos] = nums2[n]
                pos -= 1
                n -= 1

        while n >= 0:
            nums1[pos] = nums2[n]
            pos -= 1
            n -= 1
        
if __name__ == "__main__":
    nums1 = [1,2,3,0,0,0]
    m = 3
    nums2 = [2,5,6]
    n = 3
    Solution().merge(nums1, m, nums2, n)
    print(nums1)